Effect of Sm2O3 modification on Li[Li0.2Mn0.56Ni0.16Co0.08]O2 cathode material for lithium ion batteries

• Sm2O3 is well coated on Li[Li0.2Mn0.56Ni0.16Co0.08]O2 by simple wet chemical method.
• The coated sample exhibits high capacity of 234.5 mAh g−1 at 1 C.
• Capacity retention of 91.5% is obtained at 1 C (200 mA g−1) after 80 cycles 25 °C.
• EIS shows the thin Sm2O3 layer mainly reduces the charge transfer resistance.

Sm2O3-modified Li[Li0.2Mn0.56Ni0.16Co0.08]O2 was synthesized via a simple wet chemical process followed by a solid state reaction. A thin Sm2O3 layer with a thickness of about 2.5 nm was uniformly coated on the surface of the Li-rich layered oxide particles. After Sm2O3 surface modification, high discharge capacity of 214.6 mAh g−1 with a retention of 91.5% is obtained at a current density of 200 mA g−1 between 2.0 V and 4.8 V after 80 cycles. Electrochemical impedance spectroscopy (EIS) shows that the thin Sm2O3 layer mainly reduces the charge transfer resistance and stabilizes the surface structure of the active material during cycling. Sm2O3 modification will be a promising approach to improve the cyclic stability of Li-rich layered oxides.